MM 252 wire feed changes by itself.

[aametalmaster]

I have a newer MM 252 at work. About 15 months old. Say i have the wire speed set at 240 every now and then it dips to 140 by itself. At first i though someone was messing with me but i mostly work alone and no one walks by it. Today it did it twice in the 10 hours i have it on. I put a chalk line at the pointer so i can watch it and the read out. But it didn't do it anymore. I had a new lincoln inverter at my last job that did the same thing and i too though someone was messing with it then some of the other guys were having problems too and we had 6 new lincolns. Just my wondering thoughts...Bob

[aametalmaster]

I asked a few other guys at work since we have at least 50 MM252's and most of them said their machines do it too. One guy said his goes the other way where the wire runs wide open and he has to slow it down. Oh well think i will keep my non digitized machine...Bob

[Meltedmetal]

Bob
I don't have a 252, but I would like one. Could it be a worn out/loose/dirty/cheap potentiometer? Or inconsistent wire diameter or contamination on the wire resulting in slippage? Just out there guesses.
As for guy who is experiencing the opposite situation the motor controller may be intermittently losing it's reference ground. Ive been told that it is sometimes done intentionally in some motor speed controllers to accomplish full speed operation. That's a lot of MM 252's by the way.
Meltedmetal

[aametalmaster]

It could be the wire slipping i guess. We all run .045 gas flux core and some days it just gives me fits and its dirty. Seems like the flux is always coming out of the tube. I try to blow the liner out once a week. Some guys run a spool a day but i only use a spool a week as i mostly fit and tack the parts together. Tack em and stack em....Bob

[Meltedmetal]

It seems unlikely that that many machines would all suffer from the same complaint all at the same time. You haven't noticed a small troupe of gremlins following you around? They are very quick and sometimes hard to catch sight of.
On a more serious note, when the problem includes more than one manufacturer one might be inclined to think that the wire is a somehow possibility or there is a flaw in the basic speed control circuitry design for the feed motor. I'm guessing the theory at least is very similar between companies. Have you or anyone else for that matter ever heard of similar unexplained ghosts in wire feeders that are not integral to the welding machine?
Meltedmetal

[zach]

miller 252 wire feed

Mine is not a year old yet and it does the same thing. I thought it was the liner at first till i whatched the spool. Wire was brand new,name brand, solid .035.

[Meltedmetal]

Zach
So the motor slowed down when you observed the spool? I would expect wire diameter to be more consistent in solid wire than in flux core so that idea seems much less credible. Given the scope of the problem and the experience of the individuals involved it seems really unlikely to be operator error. That kind of leaves a problem with the machines and since Bob described the same problem from another manufacturer I have to wonder about the control circuit design in a welding machine environment. Intermittent problem can be real hard to nail down. If others have experienced the same problem whether or not it was on the same machine or manufacturer it would be nice if they would weigh in with the details.
Meltedmetal

[Meltedmetal]

Now that I think about a number of years ago I had a motor controller doing the same as this. Metering pump not a wire feeder. It seemed to have a mind of it's own. One day I was checking it under power and slipped with a probe, shorted out something which blew some of the copper trace off the board and toasted a diode. I relaid the trace with wire and replaced the diode and it stopped it's intermittent behavior. I assumed it was likely a cracked trace or a cold solder joint but it was too toasted by then to tell. The upside was it worked and still is for that matter.
So the problem could be defective circuit boards. I hear that since lead has been removed from solder to satisfy the EU there are more circuit board problems. Ah, progress..........Just another random thought......but all the manufacturers should get on top of this.
Meltedmetal

[zach]

yeah it slows on its own. Mine welds awesome for about 6" welding on 1/4" (25amps,500+- wire speed)then it starts slowing, going, slowing,etc. Its not running production, it is still on it's first 30lb spool of wire. Digital display doesn't change when it slows down. I've only tried adjusting tension on wire and spool spring tension. I run small welds and tacks with it here lately, till i figure it out

[aametalmaster]

Well i guess the gas flux core wire idea is out. I switched over to .035 steel a few days ago to do some sheet metal guard work and today the wire feed went the other way. It increased by itself, just the opposite of what it was doing...Bob